Numerous applications involve heat-treating a workpiece. For example, commonly-owned U.S. Pat. No. 6,594,446 discloses various methods of annealing a semiconductor wafer, which may involve, for example, pre-heating the entire wafer to an intermediate temperature at a ramp rate slower than the thermal conduction rate through the wafer, then heating the device side of the wafer at a rate much faster than the thermal conduction rate, which may be achieved by exposing the device side to an irradiance flash. As an arbitrary example, the wafer may be pre-heated to an intermediate temperature such as 700° C. for example, by irradiating the substrate side with an arc lamp to heat the entire wafer at a rate such as 400° C./second, for example. The device side may then be exposed to a high-intensity flash from a flash lamp, such as a one-millisecond flash, to heat only the device side to an annealing temperature such as 1300° C., for example. Due to the rapid heating rate of the device side during the flash (on the order of 105° C./s), the bulk of the wafer remains at the intermediate temperature, and acts as a heat sink to then cool the device side following the flash.